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Friday, February 1, 2019

In ‘Crazy
thieves in Palavakkam’ drama – a middle class family (in 1970s) would build a
small house in the outskirts of Chennai in an area called Palavakkam (now a
richman’s place)- they would be gleeful
when they see another house in distance and more so, when an odd man walks on
the street ! ~who lives next door ? 0r
whether there is life nearby has always a great curiosity of mankind !!

So is there life
nearby ! – in the nearest gruha (not as nearby home but nearby galaxy !) ..
..aGalaxy is a gravitationally bound system of stars, stellar remnants,
interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek
galaxias, literally "milky", a reference to the Milky Way. Galaxies
range in size from dwarfs with just a few hundred million (108) stars to giants
with one hundred trillion stars, each
orbiting its galaxy's center of mass.Galaxies
are categorized according to their visual morphology as elliptical,spiral, or irregular. Many galaxies are thought to have supermassive
black holes at their centers. The Milky Way's central black hole, known as
Sagittarius A*, has a mass four million times greater than the Sun.

Assembled
from a total of 7,398 exposures taken over 411 individual pointings of the
telescope, this image of our nearest major galactic neighbor, M31, is the
largest Hubble mosaic to date. The 1.5 billion pixels in the mosaic reveal over
100 million stars and thousands of star clusters embedded in a section of the
pancake-shaped disk of M31, also known as the Andromeda galaxy. Though the
galaxy is over 2 million light-years away, Hubble is powerful enough to resolve
individual stars in this 61,000-light-year-long stretch of the disk. It’s like
photographing a beach and resolving individual grains of sand !!

.. .. that story
kindled me to read something about ‘Andormeda galaxy’, also known as Messier 31, a spiral galaxy
approximately 780 kiloparsecs (2.5 million light-years) from Earth, and the
nearest major galaxy to the Milky Way. With an apparent magnitude of 3.4, the
Andromeda Galaxy is among the brightest of the Messier objects making it
visible to the naked eye on moonless nights when viewed from areas with
moderate light pollution. Its name stems
from the area of the sky in which it appears, the constellation of Andromeda.The 2006 observations by the Spitzer Space
Telescope revealed that the Andromeda Galaxy contains approximately one
trillion stars, more than twice the
number of the Milky Way's estimated 200 to 400 billion stars.It’s mass is estimated to be around 1.76 times that
of the Milky Way Galaxy .

To make us fear,
the Milky Way and Andromeda galaxies are expected to collide in ~4.5 billion
years, merging to form a giant elliptical galaxy or a large disc galaxy. Getting back to that photo – that is the largest NASA Hubble Space Telescope image ever
assembled, this sweeping bird’s-eye view of a portion of the Andromeda galaxy
(M31) is the sharpest large composite image ever taken of our galactic
next-door neighbor. Never before have
astronomers been able to see individual stars inside an external spiral galaxy
over such a large contiguous area. Most of the stars in the universe live
inside such majestic star cities, and this is the first data that reveal
populations of stars in context to their home galaxy.

Somewhat recently,
a signal detected from the neighboring
Andromeda galaxy may indicate presence of the mysterious dark matter – the
elusive substance that is believed to make up most of our universe – NASA said.
The signal is similar to one seen by the
NASA’s Fermi Gamma-ray Space Telescope at the centre of our own Milky Way
galaxy in 2014. Gamma rays are the highest-energy form of light, produced by
the universe’s most energetic phenomena. They are common in galaxies like the
Milky Way because cosmic rays, particles moving near the speed of light, produce
gamma rays when they interact with interstellar gas clouds and starlight.

Surprisingly, the latest
Fermi data shows the gamma rays in Andromeda – are confined to the galaxy’s
centre instead of spread throughout. To explain this unusual distribution,
scientists are proposing that the emission may come from several undetermined
sources. One of them could be dark matter, an unknown substance that makes up
most of the universe.Another possible
source for this emission could be a rich concentration of pulsars in M31’s centre.
These spinning neutron stars weigh as much as twice the mass of the sun and are
among the densest objects in the universe. One teaspoon of neutron star matter
would weigh a billion tons on Earth.

The similar
discovery in both the Milky Way and M31 means scientists can use the galaxies
as models for each other when making difficult observations. Recently, a group of astronomers have taken
the first steps to looking for alien life in the Andromeda galaxy as part of
new research.The project is called the
Trillion Planet Survey, and it’s being run by the University of California,
Santa Barbara. The idea is that if there’s a civilization out there that’s
purposely sending out signals, it might be possible to spot them. The team are
looking for transmissions from a civilization of “similar or higher class than
ours trying to broadcast their presence using an optical beam,” noted Andrew
Stewart from Emory University in a statement. This is known as Optical SETI
(Search for Extraterrestrial Intelligence). Based on a 2016 paper from Philip
Lubin, who’s leading the new project, the team are searching on the idea that
there’s another civilization out there that doesn’t know we’re here, but is
trying to make contact.

With photonics,
they say it could be possible to create a bright light that could be seen
across the universe. The team are now surveying Andromeda to get what they call “the pipeline” up and
running to look for such a light. Using an array of images taken by telescopes
of the Andromeda galaxy, they’re going to create a single image of the galaxy.
They will compare that image to another control image of the galaxy, which
shows no “transient signals” – events that operate on relatively short time
frames measured in years or less. If there’s a difference between their survey
photo and the control photo, it could indicate that there is some sort of
signal being transmitted. Their software is designed to remove interference
from satellites and other nearby sources.

It may
all be for naught – we could be alone, or any signals could be undetectable.
But as is often said, if we don’t try then we’ll never know.Interesting !!